The Physical Downlink Control Channel (PDCCH) is a very important downlink physical channel in the LTE system. The channel transmits downlink control information which can be used for scheduling the Physical Uplink Shared Channel (PUSCH) of the User Equipment (UE) and allocating occupied resources thereof. And, the PDCCH can also be used for informing the UE of the modulation mode of related service data, resource occupation condition etc. on the Physical Downlink Shared Channel (PDSCH). Thus, the UE can receive and decode service data correctly. The number of the Orthogonal Frequency Division Multiplexing (OFDM) symbols that the PDCCH can occupy is determined by content transmitted through the Physical Control Format Indicator Channel (PCFICH). If there is Hybrid Automatic Repeat Request (HARQ) information, part of the resources determined by PCFICH is occupied by the Physical Hybrid-ARQ Indicator Channel (PHICH), and only the rest resources are used for the PDCCH.
The LTE protocol specifies that the resources occupied by PDCCH are allocated by using the Control Channel Element (CCE) as the basic unit. In the end, the CCE is mapped to specific physical resources. Meanwhile, the protocol further specifies a corresponding relationship among PDCCH format, number of CCEs, number of Resource-Element Groups (REG) and number of PDCCH bits. However, the protocol does not specify the corresponding relationship among Downlink Control Information (DCI) format of PDCCH, CCE etc. Thus, the PDCCH resource allocation method in the related art cannot utilize the current resources reasonably, which affects the performance of entire system.